The present invention relates to a paper for receiving ink jet print and, more particularly, to an ink jet receiving paper that contains polyethylene glycol having an average molar mass of from about 30,000 to about 50,000.
Ink jet recording or printing is a process by which characters and/or graphics are recorded by depositing ink droplets ejected from an ink jet head onto a recording sheet such as, for example, a paper. Ink jet recording is advantageous because high-speed recording is possible; no noise accompanies the recording; multicolor recording is easily performed; type of pattern or image to be recorded is essentially unlimited; and no development or fixing processing is required. In addition, images obtained by multicolor ink jet recording are approaching the quality of multicolor press printed images or those images obtained by color photography.
Advancements in ink jet printing have also required advancements in recording sheets for receiving the ink jet. Improvements in recording sheets have come to be required with developments in printer hardware such as increased printing speed, the development of finer definition images of full color, and expanding fields of use. Recording sheets therefore must have high image reproducibility, the image density of the printed dots must be maintained at a high level, and hue characteristics must be bright and true. Most importantly, the applied ink must be fixed quickly without bleed or spread. In addition to image sharpness and color quality, surface aesthetics including smoothness of hard copies is also required. The recording sheet surface should be flat, smooth, and free of undulation after receiving ink.
Ink recording sheets can be classified into two basic categories: (1) noncoat type and (2) coat type. Noncoat type sheets include wood-free paper, bond, and the like. Coat type sheets have an ink-receiving layer provided on a support such as paper, synthetic paper, or synthetic resin film.
For noncoat type ink jet recording sheets, the sheet itself is required to absorb the applied ink. For this purpose, a nonsized or slightly sized paper containing some sizing agent and/or an increased amount of a loading material can be employed. However, when recording is carried out with an aqueous ink, such a recording sheet suffers from the problem that, although the sheet is superior in its ink absorbency, color quality, sharpness, and density of printed . dots and images are low and deterioration of the shape of the dot and blurring of the contour of the dot occurs. Oftentimes the applied ink permeates so deeply into the layer that ink reaches the back side of the paper.
For coat type ink jet recording sheets, the recording sheet includes a support, such as a nonsized or a slightly sized paper, and one or more coating layers. Such a recording sheet is superior in its ink absorbing properties and has improved in color quality, sharpness, and reduced feathering of the resulting images, as well as reduced strike-through of ink compared with noncoated type ink jet recording sheets. For recording sheets having a coating layer on a highly sized paper support that does not absorb aqueous ink to any significant extent, dye from the ink is retained on the surface of the recording sheet (i.e., the coating layer) and image reproducibility with excellent dot density, image density, color quality, sharpness and little feathering and strike-through can be readily obtained. However, when the amount| of coating is decreased, absorbency for the ink is low resulting in a decrease in ink absorbing rate and decreased ink absorption capacity. When the coating weight is increased to increase the absorption capacity, the bond between the coating layer and support tends to be weakened, thereby diminishing the integrity of the coated paper.
Accordingly, there exists a need for an ink jet recording paper having the advantages of high image density of printed dots, sharpness, and high color quality. A need also exists for a paper having these advantageous properties and that can be economically formed. The present invention seeks to fulfill these needs and provides further related advantages.
In one aspect, the present invention provides a paper for receiving ink jet printing. The paper has the favorable characteristics of color quality, sharpness, and high color density, and does not suffer appreciably from deterioration of the applied ink jet dot through feathering. The paper of the invention includes polyethylene glycol (PEG) having an average molar mass in the range from about 30,000 to about 50,000. In one embodiment, the paper includes polyethylene glycol having an average molar mass of about 35, 000.
In one embodiment, the invention provides a paper containing polyethylene glycol in which the polyethylene glycol is incorporated into the paper during the paper""s formation. In another embodiment of the invention, a polyethylene glycol-coated paper is provided.
In another aspect of the invention, methods for forming polyethylene glycol-containing papers are provided.